The present invention relates to wireless location systems, particularly for locating persons in distress or emergency situations.
Though the scope of the present invention is far beyond a specific system or a specific application, it may be well understood by elaborating on the case of man overboard (MOB), i.e. a person that accidentally falls overboard a vessel to the sea (or ocean, or lake, or river, etc.).
Over a thousand people are lost at sea every year due to MOB accidents. Fast detection and location of such accidents is crucial, since survival time in water is limited, typically less than two days at −20° C. and less than 6 hours at −10° C.
A reliable device to detect and locate MOB is required to save lives, but also to provide the sailor with confidence and peace of mind, as well as reducing costs and risks of Search and Rescue (SAR) operations.
The present art provides a reasonable solution for locating ships in danger of being wrecked, airplanes upon emergency landings, and in many cases also individuals in distress. This is typically accomplished by activating emergency radio beacons, detectable and locatable by satellites orbiting around the earth. Still, present SAR systems are less efficient for individuals, specifically MOB.
A major satellite SAR system presently operating worldwide is Cospas-Sarsat. Though the present invention is not limited to this specific system, Cospas-Sarsat is a good example to clarify the present art, as well as the present invention, so it is specifically enlightened here.
Cospas-Sarsat is a satellite communications system to assist SAR of people in distress, all over the world and at anytime. The system was launched in 1982 by the USA, Canada, France and the Soviet Union (Russia) and since then, it has been used for thousands of SAR events and has been instrumental in the rescue of over 20,000 lives worldwide. The goal of the system is to detect and locate signals from distress radio beacons and forward the data to ground stations, in order to support all organizations in the world with responsibility for SAR operations, whether at sea, in the air or on land.
The system uses spacecraft—Low Earth Orbit (LEO) and Geostationary (GEO) satellites; and in the future also Medium Earth Orbit (MEO) satellites; Cospas-Sarsat radio beacons transmit in the 406 MHz band (and 121.5 MHz until 2009). The position of the beacon is determined either by the Doppler shift of the received beacon signal or by position data modulated on the signal, provided by a Global Navigation Satellite System (GNSS) receiver integrated in the radio beacon.
A detailed description of the Cospas-Sarsat System is provided in the document “Introduction to the Cospas-Sarsat System, C/S G.003”, accessed through—http://cospas-sarsat.org/Documents/gDocs.htm
All Cospas-Sarsat beacons are subject to the same RF specifications, yet may employ a different mechanical structure and different activation method, possibly also slight differences in the data modulated on the signal, usually adopted to different applications, and named accordingly: a) Emergency Position Indicating Radio Beacon (EPIRB) for marine use; b) Emergency Locator Transmitter (ELT) for aviation use; and c) Personal Locator Beacon (PLB) for personal and/or terrestrial use. For the purpose of the present invention, the name “PLB” is mainly used, however it refers to any type of radio location beacon (not necessarily related to “persons”).
When activated, automatically or manually, a Cospas-Sarsat beacon transmits short signals, each about 0.5 seconds long, repetitively every 50 seconds, for at least a day, until its battery drains out.
Cospas-Sarsat beacons are already mandatory to carry onboard large ships (>300 Ton) and passenger airplanes. In several countries, also leisure yachts are required to carry such beacons.
There are various products in the market that implement Cospas-Sarsat specified beacons, for example: “ResQFix” provided by ACR (www.acrelectronics.com); “fastfind” provided by McMurdo (www.mcmurdo.co.uk); “SA50’ provided by SIMRAD (www.simradyachting.com).
Still, the problem of man overboard, which is very troublesome in the maritime arena, is not covered well enough by present art, including by present Cospas-Sarsat beacons. Since a MOB accident can happen anytime, an effective MOB device should be always carried by a person onboard, at sea, preferably worn on the body. Indeed, such wearable MOB radio beacons were been introduced to the market, for example: “LIFETAG” by Raymarine (www.raymarine.com); “WAVEFINDER” provided by Viking Life (www.viking-life.com); “MOB i-lert” provided by Ocean Safety (www.oceansafety.com), yet, these are not satellite compatible beacons, but rather short range transmitters to communicate with a receiver onboard the vessel. Some of these MOB systems can accurately record the time and position of a MOB accident, however as the vessel sails away, and turns back to the recorded MOB position, or a SAR team is dispatched to this last reported location, the poor victim could have been drifted away, even by 100-200 meters, and without an accurate updated position report, it could be very difficult to locate and rescue this person in the water, particularly in poor visibility and high sea conditions.
U.S. Pat. No. 6,545,606 to Piri et al. discloses a Device and method for alerting to the need to recover something, identifying it, and determining its location for purposes of recovery. This invention discloses a man overboard beacon, still a low power transmitting beacon (less than 15 mw in average) which is not configured to communicate with satellites.
U.S. Pat. No. 6,362,778 to Neher discloses a Personal location detection system. This invention does not disclose location methods for men overboard, and the disclosed beacon is neither configured to reach any communication satellites.
U.S. patent application 20060196499 to Cannizzaro; Kenneth Peter discloses a Scuba diver surface location, navigational and communication device and method. The disclosed device is configured to operate on local VHF networks, not with communication satellites or in a wide area network. If wearing or carrying a satellite detectable beacon, the MOB could be located accurately, by Cospas-Sarsat for example, but this information is usually not communicated to the very vessel from which the person fell overboard. This is a problem, since in case that a vessel is in the open sea, away from shore, the vessel from which a man fell overboard is the most relevant source for swift and effective rescue.
Thus, it is mostly desirable to receive onboard the vessel updated location reports from a MOB.
Yet, it is also desirable to communicate such updated location reports from a MOB to the satellite SAR system, since the MOB vessel is not always available for rescue, as in case of a single handed vessel, when persons onboard are not capable of rescuing the MOB (e.g. if the skipper fell overboard), when the vessel itself is in trouble (e.g. fire, wrecking), etc.
Apparently, incorporating present satellite beacons with present wearable MOB devices, could lead to the required solution, i.e. a wearable beacon detectable by both the satellites and the vessel.
Further, such an incorporated system seems straight forward to achieve by shrinking the size of present satellite PLBs, and installing an onboard receiver similar to those carried by Cospas-Sarsat satellites.
But such an efficient dual mode MOB system is not straight forward, for several reasons.
One reason is that design considerations good for few satellite receivers (actually, satellites usually carry transponders, and much of the receiving process is done on earth) are not optimal for mass production receivers to be installed onboard ships, and unlike satellites, the vessel receiver may lack a line of site with an MOB transmitter.
Aspects related to a receiver onboard a vessel configured to detect a satellite compatible MOB transmitter were already considered by the applicant, who proposed a method for “Determining Precise Direction and Distance to a Satellite Radio Beacon”, U.S. patent application Ser. No. 11/836,783, filed on 10 Aug. 2007.
Another reason for this non trivial incorporation is that current satellite PLB antennas are difficult to be conveniently worn by humans, while providing a good RF performance. A worn antenna should enable communicating the satellite, but disturb as less as possible the mariner, in its routine tasks, and especially when in distress.
Aspects related to a wearable antenna for a satellite compatible MOB transmitter were already considered by the applicant, who proposed a “Wrist Worn Communication Device coupled with Antenna Extendable by the Arm”, U.S. patent application Ser. No. 11/938,311, filed on 12 Nov. 2007.
Then, there is the method of activation of the MOB PLB to be effectively solved. Present PLBs are usually activated manually. Obviously, a manual activation of an MOB PLB is not desirable, since the person overboard might be unable to activate the device, being unconscious, or almost frozen, or simply focused on keeping itself above the water level. Alternatively, an automatic activation could be considered, e.g. upon water sensing.
U.S. Pat. No. 5,710,989 to Flood discloses a Water-activated emergency radio beacon.
However, an automatic activation might cause many false alarms, e.g. when a person bearing the PLB innocently jumps to swim by the boat, or washes hands onboard. Furthermore, it would be desirable, that if an MOB is swiftly rescued by the vessel from which he fell overboard, the satellite system would not be alerted, in order to avoid unnecessary SAR operations directed by the satellite system operators.
It is then an object of the present invention to provide a system and device and method for MOB, enabling detecting and locating an MOB by means installed onboard a vessel, as well as by a satellite SAR system (or satellite communication system linked to SAR capable teams).
It is also an object of the present invention to provide a system and device and method for MOB, enabling detecting and locating an MOB by means installed onboard a vessel, as well as by a satellite SAR system, even if that MOB is unconscious.
It is another object of the present invention to provide a system and device and method for MOB, significantly reducing the probability of alerting a satellite SAR system, if the MOB is swiftly rescued by the vessel from which he fell overboard.
It is yet another object of the present invention to provide a system and device and method for MOB, compatible with a satellite system for Search and Rescue, such as Cospas-Sarsat.
As already indicated, the present invention is not limited to the application of MOB and neither to Cospas-Sarsat or any other satellite SAR system. There are other scenarii that can benefit from the present invention, some of them are briefly described following.
In the military arena, the control over a group of soldiers, during a military operation, is paramount. It would be advantageous that if one of the soldiers is getting away from the group, undesirably, beyond a predefined range, the group commander would be alerted, and provided with this soldier last known location. Further, if this soldier is too distant from the group, it would be advantageous to report this soldier location to a remote headquarters, in order to enable the headquarters to better control the operation and assist this soldier, when required.
A similar logic may apply to a group of tourists, traveling in a foreign country, with a guide. Here, it would be desirable that the guide would be indicated that one of his group members is potentially lost, and provide the guide with the location of his lost sheep, in order to promptly get it back to the herd. However, if the tourist is too distant, e.g. left behind when the group took the bus, then it would be desirable to report its location to a remote station, e.g. the tourist office.
Naturally, the same logic applies to other applications and scenarii, where the location of an object, such as a person, but also an animal, pet, or valuable, is to be monitored, in reference with a fixed location, such as a home or farm or schoolyard, or in reference with a moving point, such as a vehicle or a roaming group. For example, the present invention may assist in locating a senior citizen that leaves home, potentially lost, or a cow that moves away from the corrals, or a car that is unlawfully taken away from the garage.
So, it is as well an object of the present invention to provide a system and device and method for location of an object, in reference with a predefined place, or in reference with a moving point.
It is still an object of the present invention to provide a system and device and method for location of objects such as: person, animal, pet, vehicle, weapon, ammunition, valuable asset.
One requirement which is common to the above mentioned cases of MOB and soldiers and tourists and so on, is that their location should preferably be first locally monitored, accordingly by the vessel, the commander and the tourist guide, and if successfully located at this stage, it is desirable to avoid alerting the remote station, accordingly the satellite SAR system, the military headquarters and the tourist office, as if already treated locally, it is a false alarm for the remote station.
Then, it is also an object of the present invention to provide a system and device and method for location of objects, first by a local monitoring station, and otherwise by a remote monitoring station.
So it is still another object of the present invention to provide a system and device and method for location of objects, reducing the false alarm rate at a remote monitoring station.
For MOB, an automatic activation of the location beacon is paramount, but this is also relevant to other applications, as the soldier and tourist, and is certainly relevant to a lost animal or stolen car.
So, it is nonetheless an object of the present invention to provide a system and device and method for location of objects, with an automatic activation of the device attached to the object.
Other objects and advantages of the invention will become apparent as the description proceeds.